The development of new materials with intrinsic parameters which affect electronic properties has become increasingly more important and has begun to encompass a variety of scientific disciplines. Covalent crystalline materials containing delocalized pi systems are known to exhibit interesting electronic properties when combined with other characteristics such as partially filled electronic energy levels and certain types of electron-phonon coupling. See, for example, C. Kittel, Introduction to Solid State Physics, 6th Ed., John Wiley & Sons, Inc., New York (1986), pp. 338-340. Examples of materials that have these properties are intercalated graphite and n-doped polyacetylenes described by Zhu et al., Nature, Vol. 355, pp. 712-714 (1992), p-doped polyaniline described by MacDiarmid et al., Synth. Met., 18, p. 285 (1987), sulfur nitride (SN) described by Labes et al., Chem. Rev., 79, p. 1 (1979), and intercalated C.sub.60 described by Haddon et al., Nature, Vol. 350, pp. 320-322 (1991). These materials can exhibit a range of parameters from semiconductor to metallic-like conductivities and many are superconducting. For example, the intercalated C.sub.60 material can have a superconducting conversion temperature (T.sub.C) as high as 45 K.
Some copper oxide containing compounds have been found to have a T.sub.C value as high as 125 K, which is believed to be due to planes of copper and oxygen that extend through these materials. See, R. J. Cava, Sci. Amer., 263 (2), pp. 42-49 (1990). Copper and oxygen atoms positioned within a plane form only 90.degree. and 180.degree. angles for bonding. Such bonding may have an important impact on the electronic system since the d and p electron orbitals for the atoms are orthogonal to each other. The performance of the copper oxide containing compounds has raised interest in investigating materials with a structure and dimensionality similar to a copper-oxygen plane. Materials which geometrically mimic a planar structure are Hofmann clathrates and the best known of these is Ni(CN).sub.2 NH.sub.3 .multidot.C.sub.6 H.sub.6 disclosed by Iwamoto, Inclusion Compounds, Vol. 1, pp. 29-42, Academic Press, London (1984). However, the material's electronic properties are not very interesting. It is a very good insulator and has the predicted negative resistance versus temperature slope for insulators. There is no evidence of pi delocalization over the crystal structure. It is believed the delocalized pi system in these compounds is limited and extends only over the units of Ni(CN).sub.4 !.sup.2-. Other compounds with structures which mimic a Cu-O plane are "Prussian Blues" described by Shriver et al., Inorg. Chem., 4(5), pp. 725-730 (1965). These compounds differ in the respect that the networks are three-dimensional, consisting of octahedral transition metals interlinked by linear cyanide units. These compounds are not clathrates and contain counter ions such as alkali metals in the lattice. Delocalization in these compounds is also limited and is believed to extend only over the units of M(X)(CN).sub.6 !.sup.-6+.times., wherein X is the oxidation state of the transition metal and is in general +2 or +3. It is desirable to provide compounds wherein the pi delocalization is extended further than that of the copper oxide-planes to obtain novel electronic properties.